From Diablo Wiki
Fire Chains is an Elite Affix that spawns only on Champions.
This affix creates a fiery chain that links two or three champions and that deals damage to anything it comes into contact with. This does something interesting things to combat, since players are now in danger simply by standing between two or three of the champions, even if none of them are actually touching or attacking at that moment.
The chain will only form a straight line, or a triangle if there are three champions. If there are four in the group they will be joined two and two, rather than forming some sort of trapezoid (though a four-way link may exist for short periods of time.)
Monsters with Fire Chains seem to have slightly modified AI which causes them to move around more restlessly, and makes them more likely to flank, circle, or surround enemies, increasing the chances of the dangerous chains moving over the character. The affix can create some amusing visuals as well, such as when one of the Champions is killed and sent flying into the distance, with the chain (briefly) still showing between him and the live ones.
- Monster Level Minimum: 31 (Nightmare and later)
- Available to: Champions only.
- Damage Type: Fire.
- Additional Resistances: None
The chains do not radiate or reach out, and a character will not take damage by melee fighting a monster with Fire Chains active. The danger is that another monster will move around behind your character, dragging the chain with it, or that the one you are melee fighting will circle you, taking the chain with it. And their AI seems to encourage this.
Fire Chains can also make ranged attackers more dangerous, especially the kind that move around a lot, such as Desert Wasps. Fortunately, when monsters move a long distance apart, the chains dissipate. The distance is considerable though; nearly the full visible screen, or about 80 yards apart, before the chain is disabled.
As with many boss modifiers, it's dangerous to become unable to move, and affixes like Jailer, Waller (which the chains pass over), or Nightmarish are very dangerous when Fire Chains are nearby. Other forms of AoE damage pair very well with Fire Chains as well, and Molten + Fire Chains is especially nasty for melee characters, as the monsters will circle at close range and create a double damage effect.
Fire Chained enemies are best fought in a steady retreat or by circling around the perimeter, as it's very dangerous to be within the midst of them. The chains have a maximum range of about a visible screen and will disappear if the monsters get further apart than that, though they will reform instantly and without warning if the distance closes.
 Patch Changes
Patch v1.0.4 in August 2012 reduced the damage of the Fire Chains by 20%. That patch also enabled Fire Chains for players, courtesy of the legendary item Maximus (db) that summons a demon which is connected to the player by a Fire Chain that deals damage to monsters. (The sword is a popular Follower weapon.)
Zombies with Fire Chains and Plagued
|Monsters of Diablo III Beasts Beasts: Superunique Demons Demons: Superunique Humans Humans: Superunique Undead Undead: Superunique Objects Bosses Boss Mods Monster Info Fanmade|
Bat - Beast - Blood Hawk - Demonic Hellflyer - Electric Eel - Khazra - Lacuni - Lamprey - Quill Fiend - Rockworm - Sand Monster - Sand Shark - Sand Wasp - Scavenger - Spider - Spiderling - Swarm - Withermoth - Wood Wraith -
|Primary Quest Uniques||
Act One Bosses:
Skeleton King -
The Warden -
Strong CC (Limit 1): Knockback -- Nightmarish -- Vortex -- Jailer
|Act One Uniques||Araneae - Web Spit||Leoric - Summon Skeleton, Teleport Strike, Triple Cleave||The Butcher - Smash, Grappling Hook, Spear, Frenzy Charge|
|Act Two Uniques||Maghda - Forcefield, Summoning Ritual, Punish, Moth Dust, Teleport.||Zoltan Kulle - Fiery Boulder, Time Bubble, Ceiling Collapse, Energy Twister,Vanish, Creepy Laugh||Belial - Phase One: Triple Fireball, Summon Vipers. Phase Two: Poison Meteors, Ground Pound, Lightning Strike, Lightning Breath.|
|Act Three Uniques||Ghom - Acid Slime, Sneeze, Gas Cloud, Chomp.||Siegebreaker - Triple Hit, Charge, Leg Stomp, Grab and Throw.||Cydaea - Pain Bolts, Web Trap, Spider Pits.||Azmodan - Bellyflop, Laser Attack, Falling Corpses, Demon Gate, Pool of Destruction, Globe of Annihilation.|
|Act Four Uniques||Rakanoth - Cleave, Teleport Strike, Blade Strike, Volley, Summon Minion.||Izual - Frost Nova, Frozen, Summon Minions.|| Diablo - Phase One: Claw Rip, Charge, Hell Spikes, Shadow Vanish Grab, Curse of Destruction, Ring of Fire, Ground Stomp, Curse of Anguish, Curse of Hatred. |
Phase Two: Shadow Clone. Phase Three: Overdrive, Lightning Breath.